The invention relates to the general field of power apparatus for uncoupling threaded joints in articles of heavy equipment. More particularly, the invention relates to a hydraulically-powered apparatus for uncoupling the threaded connection of large pump impellers.
Certain items of rotating heavy equipment have threaded connections which tend to tighten as the equipment is operated. For example, the threaded joints in earth drilling equipment become tight during operation and consequently are difficult to disassemble. Similarly, the impellers in large turbine pumps are connected to the lower end of the drive shaft by a threaded coupling which tightens as the pump is operated. Consequently it is difficult to remove the impeller in order to replace it or repair it.
Various power-operated apparatus have been developed to assist in breaking or uncoupling the threaded connections in such heavy equipment. Typically such apparatus are complicated and expensive to operate. For example, U.S. Pat. No. 3,256,757 inventor Kochaver discloses a power wrench for breaking the threaded joints in earth drilling equipment. This device utilizes two pipe wrenches, one anchored to the frame and a second one powered by a hydraulic cylinder. Activation of the cylinder causes one of the wrenches to rotate a portion of the drill pipe in correlation to the anchored portion. Similarly, U.S. Pat. No. 4,092,881 issued June 6, 1978, inventor Jurgens et al., discloses a power apparatus for breaking the threaded connections between drill strings. This device utilizes a stationary chuck and a rotatable chuck, with the structure of the chucks being quite involved. The particular structure for the rotatable chuck is specifically designed for tubular bodies. U.S. Pat. No. 4,295,257 issued Oct. 20, 1981 to Strohs discloses a work stand for supporting and aligning the various components of a vertical turbine pump during assembly or disassembly. The apparatus provides for the power operation of a chain wrench at any location along the work stand, using a hydraulic cylinder to power the chain wrench while a clamp assembly, using a clamping chain and a chain tightener secures the other part of the pump against rotation.
None of these power apparatus is particularly suited for unthreading the impellers of pumps. In particular, none of these apparatus is adapted to break the threaded connection of impellers of various sizes and right or left-threaded connection.
The present invention provides a power apparatus for breaking the threaded connections of various-sized and configured pump impellers. The invention comprises a V-shaped cradle for receiving the housing of the impeller, an upright vise assembly which is vertically adjustable to secure the end of the impeller shaft furthest from the impeller, and a hydraulic cylinder located on the opposite side of the cradle from the vise assembly having its lower end pivotally fixed along the axis of the apparatus and having a chain and hook connected to its upper end for hooking over a blade of the impeller. Activation of the hydraulic cylinder causes torque to be applied to the impeller blade and the threaded connection to be broken.